Dendrimer and organic light-emitting device using the same

ABSTRACT

A dendrimer and an organic light-emitting device including an organic layer having the dendrimer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.10-2010-0069170, filed on Jul. 16, 2010, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND

1. Field

The present embodiments relate to a dendrimer and an organiclight-emitting device including an organic layer having the dendrimer.

2. Description of the Related Technology

An organic light-emitting device includes an anode, a hole transportlayer, an emission layer, an electron transport layer and a cathode,which are sequentially formed on a substrate. In this regard, the holetransport layer, the emission layer, and the electron transport layerare thin films comprising organic compounds.

An organic light-emitting device is a self-emitting device in which whena current is applied to a fluorescent or phosphorescent organic layer,electrons are combined with holes in the organic layer, thereby emittinglight. Since organic light-emitting devices are lightweight, can befabricated using simple constituent elements in an easy fabricationprocess, can realize superior image quality, high color purity, anddynamic images, and operate with low power consumption, diverse researchis being conducted into organic light-emitting devices. An organiclight-emitting device may include a hole-related layer such as a holeinjection layer and a hole transport layer and an electron-related layersuch as an electron transport layer and an electron injection layer inaddition to an organic emission layer between an anode and a cathode.

Organic light-emitting devices may be manufactured using a deposition orwet process. In general, an organic material having a molecular weightof 1,000 or less is suitable for the deposition process. It is wellknown that an organic light-emitting device manufactured using alow-molecular weight compound such as a fluorene-based compound by usinga deposition process has excellent luminance. However, if an organiclight-emitting device is manufactured using a low-molecular weightcompound for deposition (such as a fluorene-based compound) by using awet process, various problems, for example, crystallization during adrying process after forming a layer may occur. When crystallization isinitiated, a start point, as a seed, extends to form a dark spot in theorganic light-emitting device. In order to prevent this crystallization,a large-size substituent or a substituent that is not crystallized maybe introduced, or an organic material having a molecular weight of aboutseveral thousands may be used to inhibit alignment or arrangement ofmolecules. A dendrimer or a polymer may be used in order to increase themolecular weight of the organic material.

Since synthesis and purification of a polymer are difficult and thepolymer has diverse molecular weights, it is difficult to regulatephysical properties, such as energy level and thermal characteristics,which determine emission characteristics. However, synthesis andpurification of a dendrimer are relatively easier than those of thepolymer and the dendrimer is a single compound of which the molecularstructure is easy to control, and thus physical properties thereof whichaffect characteristics of an organic light-emitting device may beregulated.

Therefore, there is need to develop an organic light-emitting deviceusing a dendrimer.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The present embodiments provide a dendrimer having excellent electricalstability, high charge transporting capability, and high light-emittingcapability.

The present embodiments provide an organic light-emitting deviceincluding the dendrimer.

According to an aspect of the present embodiments, there is provided adendrimer including a core unit, a bridge unit, and a dendron unit,wherein the core unit includes a trivalent or tetravalent functionalgroup selected from the group consisting of a substituted orunsubstituted C₁-C₅₀ aliphatic hydrocarbon, a substituted orunsubstituted C₅-C₅₀ aromatic hydrocarbon, and a substituted orunsubstituted C₃-C₅₀ hetero aromatic hydrocarbon,

the bridge unit includes a divalent or trivalent functional groupselected from the group consisting of a substituted or unsubstitutedC₅-C₅₀ aromatic hydrocarbon and a substituted or unsubstituted C₃-C₅₀hetero aromatic hydrocarbon, and

the dendron unit includes a monovalent fluorene-based functional grouprepresented by Formula 1 below:

where Z is selected from the group consisting of a single bond,

Ar₁ and Ar₂ are each independently selected from the group consisting ofa single bond, a substituted or unsubstituted C₅-C₅₀ aryl group, and asubstituted or unsubstituted C₃-C₅₀ heteroaryl group,

X₁ and X₂ are each independently selected from the group consisting ofnitrogen (N), boron (B), and phosphorus (P), and X′ is selected from thegroup consisting of oxygen (O), sulfur (S), SO₂, and CH₂,

Y₁, Y₂, Y₃, Y₄, Y₅, and Y₆ are each independently selected from thegroup consisting of a single bond, a substituted or unsubstituted C₁-C₅₀alkylene group, a substituted or unsubstituted C₂-C₅₀ alkenylene group,a substituted or unsubstituted C₂-C₅₀ alkynylene group, a substituted orunsubstituted C₃-C₅₀ cycloalkylene group, a substituted or unsubstitutedC₁-C₅₀ alkoxylene group, a substituted or unsubstituted C₅-C₅₀ arylenegroup, and a substituted or unsubstituted C₃ ^(-C) ₅₀ heteroarylenegroup,

R₁, R₂, R₃, R₄, and R₅ are each independently selected from the groupconsisting of a hydrogen atom, deuterium, tritium, a halogen atom, acyano group, an amino group, a nitro group, a hydroxyl group, a carboxylgroup, a substituted or unsubstituted C₁-C₅₀ alkyl group, a substitutedor unsubstituted C₂-C₅₀ alkenyl group, a substituted or unsubstitutedC₂-C₅₀ alkynyl group, a substituted or unsubstituted C₃ ^(-C) ₅₀cycloalkyl group, a substituted or unsubstituted C₁-C₅₀ alkoxy group, asubstituted or unsubstituted C₅-C₅₀ aryl group, and a substituted orunsubstituted C₃-C₅₀ heteroaryl group, and R′ and R″ are eachindependently selected from the group consisting of a hydrogen atom,deuterium, tritium, a halogen atom, a cyano group, an amino group, anitro group, a hydroxyl group, a carboxyl group, a substituted orunsubstituted C₁-C₅₀ alkyl group, a substituted or unsubstituted C₅-C₅₀aryl group, and a substituted or unsubstituted C₃-C₅₀ heteroaryl group,wherein at least two adjacent groups of R₁, R₂, R₃, R₄, R₅, R′, and R″are linked to form a saturated or unsaturated ring, and

* is a binding site between one selected from the group consisting ofAr₁, Z and a fluorene group and the bridge unit.

A number average molecular weight of the dendrimer may be from about1,000 to 300,000.

The dendrimer may further include a surface unit that is selected fromthe group consisting of a substituted or unsubstituted C₅-C₅₀ aryl groupand a substituted or unsubstituted C₃-C₅₀ heteroaryl group at the end ofthe dendron unit.

According to another aspect of the present embodiments, there isprovided an organic light-emitting device including a pair of electrodesand an organic layer interposed between the electrodes, wherein theorganic layer includes the dendrimer.

BRIEF DESCRIPTION OF THE DRAWING

The above and other features and advantages of the present embodimentswill become more apparent by describing in detail example embodimentsthereof with reference to the attached drawing in which:

FIG. 1 is a diagram of the structure of an organic light-emitting deviceaccording to an embodiment.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

A dendrimer according to an embodiment includes a core unit, a bridgeunit, and a dendron unit, wherein the core unit includes a trivalent ortetravalent functional group selected from the group consisting of asubstituted or unsubstituted C₁-C₅₀ aliphatic hydrocarbon, a substitutedor unsubstituted C₅-C₅₀ aromatic hydrocarbon, and a substituted orunsubstituted C₃-C₅₀ hetero aromatic hydrocarbon, the bridge unitincludes a divalent or trivalent functional group selected from thegroup consisting of a substituted or unsubstituted C₅-C₅₀ aromatichydrocarbon and a substituted or unsubstituted C₃-C₅₀ hetero aromatichydrocarbon, and the dendron unit includes a monovalent fluorene-basedfunctional group represented by Formula 1 below:

In Formula 1, Z is selected from the group consisting of a single bond,

wherein Z may be in a divalent oxidation state when it is linked to thebridge unit. Hereinafter, it is assumed that Z is in a divalentoxidation state when it is linked to the bridge unit.

Dendrimer is a tree-like highly branched polymer molecule comprising abranch-like unit repeatedly extending from a core unit. The dendrimerincludes a core unit positioned at the center of the entire sphericalstructure, a bridge unit regularly and repeatedly extending from thecore unit, and a dendron unit connected to the bridge unit andpositioned at the opposite side of the core unit.

In the dendrimer, the core unit that is in a trivalent or tetravalentoxidation state is positioned at the center of the entire sphericalstructure, generation is increased when the bridge unit is linked to thecore unit, and the dendron unit is positioned at the end of the bridgeunit.

The dendron unit may include a monovalent fluorene-based functionalgroup represented by Formula 1.

In Formula 1, Ar₁ and Ar₂ are each independently selected from the groupconsisting of a single bond, a substituted or unsubstituted C₅-C₅₀ arylgroup, and a substituted or unsubstituted C₃-C₅₀ heteroaryl group. Inthis regard, if Ar_(i) is linked to the bridge unit, Ar₁ is in adivalent oxidation state and may be selected from the group consistingof a C₅-C₅₀ arylene group and a substituted or unsubstituted C₃-C₅₀heteroarylene group. Hereinafter, it is assumed that Ar₁ is in adivalent oxidation state when it is linked to the bridge unit.

Ar₁ and Ar₂ are each independently selected from the group consisting ofa single bond, a phenyl group, a halophenylene group, a cyanophenylenegroup, a phenoxyphenyl group, a C₁-C₁₅ alkyl phenyl group, a di(C₁-C₁₅alkyl) phenyl group, a C₁-C₁₅ alkoxy phenyl group, a di(C₁-C₁₅ alkoxy)phenyl group, a C₅-C₁₅ aryl phenyl group, a di(C₅-C₁₅ aryl) phenylgroup, a naphthyl group, a halonaphthyl group, a cyanonaphthyl group, aphenoxynaphthyl group, a C₁-C₁₅ alkyl naphthyl group, a di(C₁-C₁₅ alkyl)naphthyl group, a C₁-C₁₅ alkoxy naphthyl group, a di(C₁-C₁₅ alkoxy)naphthyl group, a C₅-C₁₅ aryl naphthyl group, a di(C₅-C₁₅ aryl) naphthylgroup, an anthryl group, a halo-anthryl group, a cyanoanthryl group, aphenoxyanthryl group, a C₁-C₁₅ alkyl anthryl group, a di(C₁-C₁₅ alkyl)anthryl group, a C₁-C₁₅ alkoxy anthryl group, a di(C₁-C₁₅ alkoxy)anthryl group, a C₅-C₁₅ aryl anthryl group, a di(C₅-C₁₅ aryl) anthrylgroup, a phenanthryl group, a halophenanthryl group, a cyanophenanthrylgroup, a phenoxyphenanthryl group, a C₁-C₁₅ alkyl phenanthryl group, adi(C₁-C₁₅ alkyl) phenanthryl group, a C₁-C₁₅ alkoxy phenanthryl group, adi(C_(i)-C_(is) alkoxy) phenanthryl group, a C₅-C₁₅ aryl phenanthrylgroup, a di(C₅-C_(i 5) aryl) phenanthryl group, a fluorenyl group, ahalofluorenyl group, a cyanofluorenyl group, a phenoxyfluorenyl group, aC₁-C₁₅ alkyl fluorenyl group, a di(C₁-C₁₅ alkyl) fluorenyl group, aC₁-C₁₅ alkoxy fluorenyl group, a di(C₁-C₁₅ alkoxy) fluorenyl group, aC₅-C₁₅ aryl fluorenyl group, a di(C₅-C₁₅ aryl) fluorenyl group, apyridyl group, a halopyridyl group, a cyanopyridyl group, aphenoxypyridyl group, a C₁-C₁₅ alkyl pyridyl group, a di(C_(i)-C_(is)alkyl) pyridyl group, a C_(I)-Q_(s) alkoxy pyridyl group, a di(C₁-C₁₅alkoxy) pyridyl group, a C₅-C₁₅ aryl pyridyl group, a di(C_(s)-C_(is)aryl) pyridyl group, a pyrenyl group, a halopyrenyl group, acyanopyrenyl group, a phenoxypyrenyl group, a C₁-C₁₅ alkyl pyrenylgroup, a di(C₁-C₁₅ alkyl) pyrenyl group, a C₁-C₁₅ alkoxy pyrenyl group,a di(C₁-C₁₅ alkoxy) pyrenyl group, a C₅-C₁₅ aryl pyrenyl group, adi(C₅-C₁₅ aryl) pyrenyl group, a phenanthrolinyl group, ahalophenanthrolinyl group, a cyanophenanthrolinyl group, aphenoxyphenanthrolinyl group, a C₁-C₁₅ alkyl phenanthrolinyl group, adi(C₁-C₁₅ alkyl) phenanthrolinyl group, a C₁-C₁₅ alkoxy phenanthrolinylgroup, a di(C₁-C₁₅ alkoxy) phenanthrolinyl group, a C₅-C₁₅ arylphenanthrolinyl group, a di(C₅-C₁₅ aryl) phenanthrolinyl group, aquinolinyl group, a haloquinolinyl group, a cyanoquinolinyl group, aphenoxyquinolinyl group, a C₁-C₁₅ alkyl quinolinyl group, a di(C₁-C₁₅alkyl) quinolinyl group, a C₁-C₁₅ alkoxy quinolinyl group, a di(C₁-C₁₅alkoxy) quinolinyl group, a C₅-C₁₅ aryl quinolinyl group, a di(C₅-C₁₅aryl) quinolinyl group, a carbazolyl group, a halocarbazolyl group, acyanocarbazolyl group, a phenoxycarbazolyl group, a C₁-C₁₅ alkylcarbazolyl group, a di(C₁-C₁₅ alkyl) carbazolyl group, a C₁-C₁₅ alkoxycarbazolyl group, a di(C₁-C₁₅ alkoxy) carbazolyl group, a C₅-C₁₅ arylcarbazolyl group, and a di(C₅-C₁₅ aryl) carbazolyl group.

For example, Ar₁ and Ar₂ may be each independently a single bond, aphenyl group, a halophenylene group, a cyanophenylene group, a biphenylgroup, a dimethylfluorenyl group, a carbazolyl group, and adiphenylcarbazolyl group.

In Formula 1, X₁ and X₂ may be each independently selected from thegroup consisting of nitrogen (N), boron (B) and phosphorus (P). Forexample, both of X₁ and X₂ may be nitrogen (N).

In addition, X′ may be selected from the group consisting of oxygen (O),sulfur (S), SO₂, and CH₂. For example, X′ may be sulfur (S).

In Formula 1, Y₁ to Y₆ may be each independently selected from the groupconsisting of a single bond, a substituted or unsubstituted C₁-C₅₀alkylene group, a substituted or unsubstituted C₂-C₅₀ alkenylene group,a substituted or unsubstituted C₂-C₅₀ alkenylene group, a substituted orunsubstituted C₃-C₅₀ cycloalkylene group, a substituted or unsubstitutedC₁-C₅₀ alkoxylene group, a substituted or unsubstituted C₅-C₅₀ arylenegroup, and a substituted or unsubstituted C₃ ^(-C) ₅₀ heteroarylenegroup.

Y₁ to Y₆ may be each independently selected from the group consisting ofa single bond, a methyl group, an ethyl group, a propyl group, anisobutyl group, a sec-butyl group, a phenyl group, a methylphenyl group,an ethylphenyl group, an o-, m- and p-fluorophenyl group, adichlorophenyl group, a cyanophenyl group, a dicyanophenyl group, atrifluoromethoxyphenyl group, a biphenyl group, a halobiphenyl group, acyanobiphenyl group, a methylbiphenyl group, an ethylbiphenyl group, amethoxybiphenyl group, and an ethoxybiphenyl group.

For example, Y₁ to Y₆ may be each independently a single bond, a methylgroup, an ethyl group, a propyl group, an isobutyl group, a sec-butylgroup, a phenyl group, or a diphenyl group.

In Formula 1, R₁, to R₅ may be each independently selected from thegroup consisting of a hydrogen atom, deuterium, tritium, a halogen atom,a cyano group, an amino group, a nitro group, a hydroxyl group, acarboxyl group, a substituted or unsubstituted C₁-C₅₀ alkyl group, asubstituted or unsubstituted C₂-C₅₀ alkenyl group, a substituted orunsubstituted C₂-C₅₀ alkynyl group, a substituted or unsubstitutedC₃-C₅₀ cycloalkyl group, a substituted or unsubstituted alkoxy group, asubstituted or unsubstituted C₅-C₅₀ aryl group, and a substituted orunsubstituted C₃-C₅₀ heteroaryl group, and R′ and R″ may be eachindependently selected from the group consisting of a hydrogen atom,deuterium, tritium, a halogen atom, a cyano group, an amino group, anitro group, a hydroxyl group, a carboxyl group, a substituted orunsubstituted C₁-C₅₀ alkyl group, a substituted or unsubstituted C₅-C₅₀aryl group, and a substituted or unsubstituted C₃-C₅₀ heteroaryl group,wherein at least two adjacent groups of R₁, R₂, R₃, R₄, R₅, R′ and R″are linked to form a saturated or unsaturated ring.

R₁, R₂, R₃, R₄, R₅, R′ and R″ may be each independently selected fromthe group consisting of a hydrogen atom, deuterium, tritium, a halogenatom, a cyano group, an amino group, a methyl group, an ethyl group, apropyl group, an isobutyl group, a sec-butyl group, a phenyl group, amethylphenyl group, an ethylphenyl group, an o-, m- and p-fluorophenylgroup, a dichiorophenyl group, a cyanophenyl group, a dicyanophenylgroup, a trifluoromethoxyphenyl group, a biphenyl group, a halobiphenylgroup, a cyanobiphenyl group, a methylbiphenyl group, an ethylbiphenylgroup, a methoxybiphenyl group, and an ethoxybiphenyl group.

For example, R₁, R₂, R₃, R₄, R₅, R′ and R″ may be each independently ahydrogen atom, deuterium, tritium, a halogen atom, a cyano group, anamino group, a methyl group, an ethyl group, a propyl group, an isobutylgroup, a sec-butyl group, a phenyl group, or a biphenyl group.

In Formula 1, * is a binding site between one selected from the groupconsisting of Ar₁, Z, and a fluorene group and the bridge unit. Forexample, * may be a binding site between Ar1 of Formula 1 and the bridgeunit, between Z and the bridge unit, or between a fluorene group and thebridge unit.

The monovalent fluorene-based functional group represented by Formula 1may have at least one fluorene group and one phenothiazine group and maybe used for an organic layer of an organic light-emitting device.

The phenothiazine group has diverse bandgaps according to X′ (O, S, SO₂,or CH₂) as an EML-forming material or hole transporting material.Accordingly, a compound including a phenothiazine group exhibitsexcellent electrical characteristics in an organic light-emittingdevice, and the organic light-emitting device including the compound hasexcellent luminance and long life-span. In addition, a carbazol grouplinked to an amine group in the compound is efficiently used to injectand transport holes and has excellent electrical stability. The fluorenegroup facilitates transfer of singlet excitons. Thus, if a compoundincluding the fluorene group is used in an emission layer of an organiclight-emitting device, the intensity of fluorescence increases toimprove luminance. If the compound including the fluorene group is usedas a host material of a fluorescent or phosphorescent dopant, energytransfer to a dopant increases to improve luminance. In addition, thefluorene group has diverse solubility in a solvent according to R₁ andR₂, and thus may be efficiently used in a wet process.

For example, the dendron unit may include one selected from the groupconsisting of the functional groups represented by Formulae 2 to 5.

In Formulae 2 to 5, * is a binding site with the bridge unit.

In the dendrimer, the bridge unit is linked to the dendron unit via thebinding site to increase generation.

The bridge unit is in a divalent or trivalent oxidation state and may belinked to an adjacent core unit or dendron unit via the binding site. Ifa plurality of bridge units are consecutively connected, the bridge unitmay be linked to another bridge unit.

The bridge unit may be any divalent or trivalent linking group capableof linking adjacent units without inducing side reactions during thereaction with the dendron unit including the fluorene-based functionalgroup. The bridge unit may include O and S to improve stability of afinal product.

The bridge unit may include a divalent or trivalent functional groupselected from the group consisting of a substituted or unsubstitutedC₅-C₅₀ aromatic hydrocarbon and a substituted or unsubstituted C₃-C₅₀hetero aromatic hydrocarbon, and for example, a C₃-C₅₀ hetero aromatichydrocarbon including a carbazolyl group in which at least one hydrogenatom is substituted with an oxygen (O) atom or a nitrogen (N) atom.

For example, the bridge unit may include one selected from the groupconsisting of the functional groups represented by Formulae 6 to 9.

In Formulae 6 to 9, ** is a binding site with an adjacent unit. ** maybe a binding site with the core unit, the dendron unit, or the bridgeunit. If ** is a binding site with the bridge unit, the bridge units areconsecutively linked to each other.

The dendrimer according to an embodiment includes the core unit at thecenter of the entire spherical structure to be connected to the bridgeunit.

The core unit may be in the trivalent or tetravalent oxidation state andlinked to the bridge unit via the binding site.

The core unit may include a trivalent or tetravalent functional groupselected from the group consisting of a substituted or unsubstitutedC₁-C₅₀ aliphatic hydrocarbon, a substituted or unsubstituted C₅-C₅₀aromatic hydrocarbon, and a substituted or unsubstituted C₃-C₅₀ heteroaromatic hydrocarbon,

For example, the core unit may include one selected from the groupconsisting of the functional groups represented by Formulae 10 to 12.

In Formulae 10 to 12, *** is a binding site with the bridge unit.

A number average molecular weight of the dendrimer including the coreunit, the bridge unit, and the dendron unit may be from about 1,000 to300,000.

The degree of branching of the dendrimer refers to a rate of a totalnumber of the core unit and the dendrimer to a total number of the coreunit, the bridge unit, and the dendron unit. For example, if the degreeof branching is 0, the dendrimer is a linear molecule only having thebridge unit without the core unit and the dendron unit. If the degree ofbranching is 1, the bridge unit does not exist, and thus the dendronunit does not exist, either. The degree of branching may be calculatedbased on a ratio of integral values for the peaks of the nuclearmagnetic resonance (NMR) spectra of the core unit, the bridge unit, andthe dendron unit. The degree of branching of the dendrimer may varyaccording to reaction temperature, reaction time, solvent, and the like.

The dendrimer may further include a surface unit that is selected fromthe group consisting of a substituted or unsubstituted C₅-C₅₀ aryl groupand a substituted or unsubstituted C₃-C₅₀ heteroaryl group.

For example, the dendrimer may further include a surface unit connectedto a fluorene-based functional group represented by Formula 18 below:

In Formula 18, Z is selected from the group consisting of a single bond,

and Ar₁, Ar₂, X₁, X₂, Y₁, Y₂, Y₃, Y₄, Y₅, Y₆, R₁, R₂, R₃, R₄, R₅, R′,and R″ are described above with reference to Formula 1. In this regard,one of * and **** is a binding site with the bridge unit and the otheris a binding site with the surface unit.

The surface unit that is a unit independently connected to the dendronunit and positioned at the end (surface) of the dendron unit may beselected from the group consisting of a substituted or unsubstitutedC₅-C₅₀ aryl group and a substituted or unsubstituted C₃-C₅₀ heteroarylgroup.

For example, the surface unit may be a phenyl group, a halophenylenegroup, a cyanophenylene group, a biphenyl group, a dimethylfluorenylgroup, a carbazolyl group, or a diphenylcarbazolyl group.

The dendrimer including the core unit, the bridge unit, and the dendronunit including a functional group represented by Formula 1 may beDendrimers 1 to 5. However, the dendrimer is not limited to thefollowing formulae.

The unsubstituted C₁-C₅₀ alkyl group used herein may be a linear orbranched group. Examples of the unsubstituted C₁-C₅₀ alkyl groupinclude, but are not limited to, methyl, ethyl, propyl, isobutyl,sec-butyl, pentyl, iso-amyl, hexyl, heptyl, octyl, nonanyl, and dodecyl.At least one hydrogen atom of the C₁-C₅₀ alkyl group may be substitutedwith deuterium, tritium, a halogen atom, a cyano group, an amino group,an amidino group, a nitro group, a hydroxyl group, a hydrazinyl group, ahydrazonyl group, a carboxyl group or a salt thereof, a sulfonic acidgroup or a salt thereof, a phosphoric acid or a salt thereof, a C₁-C₃₀alkyl group, a C₁-C₃₀ alkoxy group, a C₂-C₃₀ alkenyl group, a C₂-C₃₀alkynyl group, a C₅-C₂₀ aryl group, a C₃-C₂₀ heteroaryl group,—N(Q₁)(Q₂), or —Si(Q₃)(Q₄)(Q₅), Here, Q₁ through Q₅ may be eachindependently a hydrogen atom, deuterium, tritium, a halogen atom, acyano group, an amino group, an amidino group, a nitro group, a hydroxylgroup, a hydrazinyl group, a hydrazonyl group, a carboxyl group or asalt thereof, a sulfonic acid group or a salt thereof, a phosphoric acidor a salt thereof, a C₁-C₃₀ alkyl group, a C₁-C₃₀ alkoxy group, a C₂-C₃₀alkenyl group, a C₂-C₃₀ alkynyl group, a C₅-C₂₀ aryl group, or a C₃-C₂₀heteroaryl group.

The unsubstituted C₂ ^(-C) ₅₀ alkenyl group used herein indicates ahydrocarbon chain having at least one carbon-carbon double bond at thecenter or at a terminal of the unsubstituted C₂-C₅₀ alkyl group.Examples of the unsubstituted C₂-C₅₀ alkenyl group include ethenyl,propenyl, butenyl, and the like. At least one hydrogen atom in theunsubstituted C₂-C₅₀ alkenyl group may be substituted with thesubstituents described in connection with the substituted C₁-C₅₀ alkylgroup.

The unsubstituted C₂-C₅₀ alkynyl group used herein indicates ahydrocarbon chain having at least one carbon-carbon triple bond at thecenter or at a terminal of the C₂-C₅₀ alkyl group defined above.Examples of the unsubstituted C₂-C₂₀ alkynyl group include acetylene,propylene, phenylacetylene, naphthylacetylene, isopropylacetylene,t-butylacetylene, and diphenylacetylene. At least one hydrogen atom inthe unsubstituted C₂-C₂₀ alkynyl group may be substituted with thesubstituents described above in connection with the C₁-C₅₀ alkyl group.

The unsubstituted C₃-C₅₀ cycloalkyl group used herein refers to a C₃-C₅₀cyclic alkyl group wherein at least one hydrogen atom in the C₃-C₅₀cycloalkyl group may be substituted with substituents described above inconnection with the C₁-C₅₀ alkyl group.

The unsubstituted C₁-C₅₀ alkoxy group used herein is a group having astructure of −OA wherein A is an unsubstituted C₁-C₅₀ alkyl group asdescribed above. Examples thereof include methoxy, ethoxy, propoxy,isopropyloxy, butoxy, and pentoxy. At least one hydrogen atom of theC₁-C₅₀ alkoxy group may be substituted with the same substituent groupsas described above in connection with the C₁-C₅₀ alkyl group.

The unsubstituted C₅-C₅₀ aryl group used herein refers to a carbocyclicaromatic system containing at least one ring. At least two rings may befused to each other or linked to each other by a single bond. The term‘aryl’ refers to an aromatic system, such as phenyl, naphthyl, oranthracenyl. At least one hydrogen atom in the C₅-C₅₀ aryl group may besubstituted with the substituents described above in connection with theC₁-C₅₀ alkyl group. Examples of the substituted or unsubstituted C₅-C₃₀aryl group include, but are not limited to, a phenyl group, a C₁-C₁₀alkylphenyl group (for example, an ethylphenyl group), a halophenylgroup (for example, an o-, m-, and p-fluorophenyl group, adichlorophenyl group), a cyanophenyl group, dicyanophenyl group, atrifluoromethoxyphenyl group, a biphenyl group, a halobiphenyl group, acyanobiphenyl group, a C₁-C₁₀ alkyl biphenyl group, a C₁-C₁₀alkoxybiphenyl group, a o-, m-, and p-toryl group, an o-, m-, andp-cumenyl group, a mesityl group, a phenoxyphenyl group, a(α,α-dimethylbenzene)phenyl group, a (N,N′-dimethyl)aminophenyl group, a(N,N-diphenyl)aminophenyl group, a pentalenyl group, an indenyl group, anaphthyl group, a halonaphthyl group (for example, a fluoronaphthylgroup), a C₁-C₁₀ alkylnaphthyl group (for example, a methylnaphthylgroup), a C₁ -C₁₀ alkoxynaphthyl group (for example, a methoxynaphthylgroup), a cyanonaphthyl group, an anthracenyl group, an azulenyl group,a heptalenyl group, an acenaphthylenyl group, a phenalenyl group, afluorenyl group, an anthraquinolyl group, a methylanthryl group, aphenanthryl group, a triphenylene group, a pyrenyl group, a chrycenylgroup, an ethyl-chrysenyl group, a picenyl group, a perylenyl group, achloroperylenyl group, a pentaphenyl group, a pentacenyl group, atetraphenylenyl group, a hexaphenyl group, a hexacenyl group, arubicenyl group, a coronelyl group, a trinaphthylenyl group, aheptaphenyl group, a heptacenyl group, a pyranthrenyl group, and anovalenyl group.

The unsubstituted C₃-C₅₀ heteroaryl group used herein includes one, twoor three hetero atoms selected from among N, O, P, and S. At least tworings may be fused to each other or linked to each other by a singlebond. Examples of the unsubstituted C₃-C₅₀ heteroaryl group may includea pyrazolyl group, an imidazolyl group, an oxazolyl group, a thiazolylgroup, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, apyridinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinylgroup, a carbazolyl group, an indolyl group, a quinolinyl group, and anisoquinolinyl group. At least one hydrogen atom in the C₃-C₅₀ heteroarylgroup may be substituted with the substituents described above inconnection with the C₁-C₅₀ alkyl group.

The unsubstituted C₁-C₅₀ aliphatic hydrocarbon functional group may be alinear or branched C₁-C₅₀ alkyl group. Examples of the unsubstitutedC₁-C₅₀ aliphatic hydrocarbon include, but are not limited to, methyl,ethyl, n-propyl, i-propyl, n-butyl, s-butyl, i-butyl, t-butyl, pentyl,hexyl, heptyl, octyl, nonanyl, and dodecyl. At least one hydrogen atomof the C₁-C₅₀ aliphatic hydrocarbon functional group may be substitutedwith deuterium, tritium, a halogen atom, a cyano group, an amino group,an amidino group, a nitro group, a hydroxyl group, a hydrazinyl group, ahydrazonyl group, a carboxyl group or a salt thereof, a sulfonic acidgroup or a salt thereof, a phosphoric acid or a salt thereof, a C₁-C₃₀alkyl group, a C₁-C₃₀ alkoxy group, a C₂-C₃₀ alkenyl group, and a C₂-C₃₀alkynyl group.

The unsubstituted C₅-C₅₀ aromatic hydrocarbon functional group usedherein is the same as the C₅-C₅₀ aryl group and may be substituted withthe substituents described above in connection with the C₁-C₅₀ alkylgroup.

The unsubstituted C₃-C₅₀ hetero aromatic hydrocarbon functional groupused herein is the same as the C3-C₅₀ heteroaryl group and may besubstituted with the substituents described above in connection with theC₁-C₅₀ alkyl group.

Throughout the specification, a saturated ring or unsaturated ringformed by the linking of at least two adjacent substituents indicates asubstituent including at least two rings formed by the fusing of atleast one aromatic ring and/or at least one non-aromatic ring. Examplesof this substituent include some of the substituents described above inconnection with the aryl group or heteroaryl group.

An organic light-emitting device according to another embodimentincludes a first electrode; a second electrode disposed opposite to thefirst electrode; and an organic layer between the first electrode andthe second electrode, wherein the organic layer includes a dendrimerincluding a dendron unit represented by Formula 1 described above.

Hereinafter, an organic light-emitting device including the dendrimeraccording to an embodiment will be described.

FIG. 1 is a diagram of the structure of an organic light-emitting deviceaccording to an embodiment.

First, an anode-forming material having a high work function isdeposited or sputtered on a substrate to form an anode. The substratemay be a substrate conventionally used in organic light-emittingdevices, and may include, for example, a glass substrate or atransparent plastic substrate with excellent mechanical strength,thermal stability, transparency, surface smoothness, ease of handling,and water resistance. The anode-forming material may be ITO, IZO, SnO₂,or ZnO, which are transparent and highly conductive.

Then, a hole injection layer (HIL) is formed on the anode by using avacuum deposition, a spin coating, a casting, or a Langmuir-Blodgett(LB) method. However, when the HIL is formed using vacuum deposition,the HTL may be uniform, and occurrence of pin holes may be suppressed.When the HIL is formed by vacuum deposition, deposition conditions mayvary according to a compound that is used to form the HIL, and accordingto the structure and thermal properties of the HIL to be formed. Ingeneral, however, conditions for vacuum deposition may include adeposition temperature ranging from about 50 to about 500° C., apressure ranging from about 10⁻⁸ to about 10⁻³ torr, a deposition speedranging from about 0.01 to about 100 Å/sec, and a layer thicknessranging from about 10 Å to about 5 μm. A material used to form the HILmay be any known hole injecting material, e.g., a phthalocyaninecompound (e.g., copper phthalocyanine) disclosed in U.S. Pat. No.4,356,429 or a Starburst-type amine derivative (e.g., TCTA, m-MTDATA, orm-MTDAPB) disclosed in Advanced Material, 6, p. 677(1994).

A hole transport layer (HTL) may be formed on the HIL by using a vacuumdeposition, a spin coating, a casting, or an LB method. However, whenthe HTL is formed using vacuum deposition, the HTL may be uniform, andoccurrence of pin holes may be suppressed. When the HTL are formed usingvacuum deposition, the deposition conditions may be similar to those forthe formation of the HIL, although the deposition and coating conditionsmay vary according to a material that is used to form the HTL. Amaterial used to form the HTL may be any known hole transportingmaterial, e.g., a dendrimer compound including a dendron unitrepresented by Formula 1. Examples of the HTL-forming material include,but are not limited to, cabazol derivatives such as N-phenylcarbazol orpolyvinylcarbazol, and amine derivatives having an aromatic condensedring, such asN,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine(TPD), and N,N′-di(naphthalene-1-yl) -N,N′-diphenyl benzidine (a-NPD).The thickness of the HTL may be from about 50 to about 1,000 Å, forexample, about 100 to about 600 Å. When the thickness of the HTL iswithin the above range, the HTL may have excellent hole transportcharacteristics without a substantial increase in driving voltage.

An emission layer (EML) may be formed on the HTL by using vacuumdeposition, spin coating, casting, or LB deposition. However, when theEML is formed using vacuum deposition, the EML may be uniform, andoccurrence of pin holes may be suppressed. When the EML is formed byusing vacuum deposition, the deposition conditions may be similar tothose for the formation of the HIL, although the deposition conditionsmay vary according to the material that is used to form the EML. As anEML-forming material, a dendrimer compound including a dendron unitrepresented by Formula 1 may be used alone or as a host, but theEML-forming material is not limited thereto.

If the dendrimer compound including the dendron unit represented byFormula 1 is used as an emission host, the EML may be used using thedendrimer compound with a phosphorescent or fluorescent dopant. In thisregard, the fluorescent dopant may be IDE102 or IDE105 purchased byIdemitsu. Examples of green phosphorescent dopants may include, but arenot limited to, Ir(ppy)₃, where “ppy” denotes phenylpyridine,Ir(ppy)₂(acac), Ir(mpyp)₃, and C545T. Examples of blue phosphorescentdopants include, but are not limited to, F₂lrpic, (F₂ppy)₂Ir(tmd),Ir(dfppz)₃, ter-fluorene, 4,4′-bis(4-diphenylaminostyryl)biphenyl(DPAVBi), and 2,5,8,11-tetra-t-butyl pherylene (TBPe). Examples of redphosphorescent dopants may include, but are not limited to, platinum(II)octaethylporphyrin (PtOEP), Ir(piq)₃, Btp₂Ir(acac), DCJTB, and RD61produced by UDC.

The doping concentration of a dopant is not particularly limited. Thecontent of the dopant may be from about 0.01 to about 15 parts by weightbased on 100 parts by weight of the host. If the content of the dopantis within the above range, the EML may have excellent light-emittingcharacteristics and concentration quenching may be substantiallyprevented. When the EML includes a phosphorescent dopant, a holeblocking material may be further deposited or spin-coated on the EML toprevent diffusion of triplet excitons or holes into an electrontransport layer (ETL). In this case, the hole blocking material may beany known material that is commonly used in the art without limitation.For example, the hole blocking material may include an oxadiazolederivative, a triazole derivative, a phenanthroline derivative, a holeblocking material disclosed in Japanese Patent

No. hei 11-329734(A1), the contents of which are incorporated herein byreference, and for example, Balq represented by the following formula,and phenanthrolines (e.g.,: BCP produced by UDC).

The thickness of the EML may be from about 100 to about 1,000 Å, forexample, about 200 to about 600 Å. When the thickness of the EML iswithin these ranges, the EML may have excellent light-emittingcharacteristics without a substantial increase in driving voltage.

Alternatively, when the EML includes a phosphorescent dopant, a HBL (notshown in FIG. 1) including the hole blocking material may be formed onthe EML in order to prevent diffusion of triplet excitons or holes intothe ETL for the same purpose of adding the hole blocking material to theEML.

An ETL may be formed on the EML by using vacuum deposition, spincoating, casting, or the like, for example, vacuum deposition. AnETL-forming material may be any material capable of stably transportingelectrons injected from the electron injection electrode (cathode), forexample, a quinoline derivative, particularly,tris(8-quinolinorate)aluminum (Alq3). In addition, an electron injectionlayer (EIL) may be formed on the ETL using any material that allowselectrons to be easily injected from the cathode. The EIL may compriseLiF, NaCl, CsF, Li₂O, BaO, or the like. The thickness of the ETL may bein a range of about 100 to about 1,000 Å, for example, about 100 toabout 500 Å. When the thickness of the ETL is within the above range,the ETL may have excellent electron transport characteristics without asubstantial increase in driving voltage.

Deposition conditions for forming the HBL, ETL, and EIL are similar tothose used to form the HIL, although the deposition conditions may varyaccording to the material that is used to form the HBL, ETL, and EIL.

Finally, a cathode-forming metal is formed on the EIL by using vacuumdeposition or sputtering to form a cathode. Examples of thecathode-forming metal include a metal, an alloy, and an electricallyconductive compound and a mixture thereof. Examples of such materialsinclude lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium(Al—Li), calcium (Ca), magnesium-indium(Mg—In), and magnesium-silver(Mg—Ag). In addition, a transparent cathode comprising ITO or IZO may beused to manufacture a top-emission light-emitting device.

According to embodiments, the organic light-emitting device may have thestructure of FIG. 1 in which the anode, the HIL, the HTL, the EML, theETL, the EIL, and the cathode are stacked on one another. However, theorganic light-emitting device may have any of a variety of structures.For example, the organic light-emitting device may further include oneor two intermediate layers, if needed. The HIL, EIL, and HBL are notessential but may improve emission efficiency.

Hereinafter, a dendrimer including a fluorene-based functional grouprepresented by Formula 1 and having at least one fluorene group and onephenothiazine group as side chains will be described more fully withreference to the following synthesis examples and examples. However, thefollowing examples are only for illustrative purpose and are notintended to limit the scope of the embodiments. The dendrimer hasexcellent emitting and hole transporting capabilities and may be used asa blue emitting material, green and red phosphorescent host materials,green and red fluorescent host materials, and a hole transportingmaterial.

SYNTHESIS EXAMPLE 1 Synthesis of Dendrimer 2

A mixture including 18.3 g (100.0 mmol) of 10H-phenoxazine, 21.6 g(200.0 mmol) of bromo ethane, 12.0 g (120.0 mmol) of Et3N, and 600 mL ofTHF was stirred at 60° C. for 12 hours in a nitrogen atmosphere. 200 mLof water was added to the reaction mixture, and the reaction mixture wassubjected to extraction twice with 500 mL ethyl acetate. An organiclayer was dried, filtered, concentrated, and then separated using columnchromatography to obtain 18.2 g of Compound C-1 in light-yellow liquidform with a yield of 86%. The structure of Compound C-1 was identifiedusing high-resolution mass spectrometry (HR-MS). (calc.: 211.0997,found: 211.0986)

400 mL of acetic acid was added to a mixture including 21.1 g (100.0mmol) of Compound C-1, 13.4 g (50.3 mmol) of iodine, and 2.2 g (10.0mmol) of periodic acid, and the mixture was maintained at 80° C. for 4hours. 500 mL of cold water was added to the reaction mixture, and thereaction mixture was stirred and filtered. A solid phase obtained by thefiltration was cleaned with cold water several times. Then, the solidphase was dissolved in 400 mL of ethyl ether, dried, filtered,concentrated, and then separated using column chromatography to obtain25.2 g of Compound C-2 in a pale yellow solid form with a yield of75.1%. The structure of Compound C-2 was identified using HR-MS. (calc.:33.9964, found: 336.9952)

100 mL of toluene was added to a mixture including 10.1 g (30.0 mmol) ofCompound C-2, 10.1 g (39.0 mmol) of Compound C-3, 4.3 g (45.0 mmol) ofNaOtBu, 1.4 g (1.5 mmol) of Pd₂(dba)₃, and 0.30 g (1.5 mmol) of PtBu₃and then the mixture was maintained at 90° C. in a nitrogen atmospherefor 6 hours. The reaction mixture was cooled to room temperature, 30 mLof water was further added to the reaction mixture, and the reactionmixture was subjected to extraction twice with 200 mL of methylenechloride. An organic layer was dried, filtered, concentrated, and thenseparated using column chromatography to obtain 8.38 g of Compound C-4in light-yellow solid form with a yield of 62%. The structure ofCompound C-4 was identified using HR-MS. (calc.: 467.1998, found:467.1987)

100 mL of toluene was added to a mixture including 14.0 g (30.0 mmol) ofCompound C-4, 15.6 g (39.0 mmol) of Compound C-5, 4.3 g (45.0 mmol) ofNaOtBu, 1.4 g (1.5 mmol) of Pd₂(dba)₃, and 0.30 g (1.5 mmol) of PtBu₃and then the mixture was maintained at 90° C. in a nitrogen atmospherefor 6 hours. The reaction mixture was cooled to room temperature, 30 mLof water was further added to the reaction mixture, and the reactionmixture was subjected to extraction twice with 200 mL of methylenechloride. An organic layer was dried, filtered, concentrated, and thenseparated using column chromatography to obtain 17.1 g of Compound C-6in light-yellow solid form with a yield of 77%. The structure ofCompound C-6 was identified using HR-MS. (calc.: 737.2042, found:737.2032)

100 mL of toluene was added to a mixture including 22.1 g (30.0 mmol) ofCompound C-6, 9.1 g (36.0 mmol) of bis(pinacolato)diboron, 1.2 g (0.05mole%) of Pd(dppf)Cl₂, and 3.5 g (36.0 mmol) of KOtBu, and then themixture was maintained at 90° C. in a nitrogen atmosphere for 6 hours.The reaction mixture was cooled to room temperature, 50 mL of water wasfurther added to the reaction mixture, and the reaction mixture wassubjected to extraction twice with 300 mL of methylene chloride. Anorganic layer was dried, filtered, concentrated, and then separatedusing column chromatography to obtain 13.2 g of Compound C-7 inpale-yellow solid form with a yield of 56%. The structure of CompoundC-7 was identified using FIR-MS. (calc.: 785.3789, found: 785.3774)

100 mL of tetrahydrofuran (THF) was added to a mixture including 1.56 g(30 mmol) of Compound C-8, 12.7 g (14.0 mmol) of Compound C-7, 0.69 g (5mol%) of Pd(PPh₃)₄, 4.8 g (120 mmol) of NaOH, and 30 mL of water, andthen the mixture was maintained at 70° C. in a nitrogen atmosphere for36 hours. The reaction mixture was cooled to room temperature, 50 mL ofwater was further added to the reaction mixture, and the reactionmixture was subjected to extraction twice with 300 mL of methylenechloride. An organic layer was dried, filtered, concentrated, and thenrecrystallized using column chromatography to obtain 2.97 g of Dendrimer2 in pale-yellow solid form with a yield of 35%. The structure ofDendrimer 2 was identified using nuclear magnetic resonance (NMR)spectroscopy. 1H-NMR (CDCl₃, 400 MHz) δ (ppm); 1.24 (t, 18H), 1.87 (s,36H), 3.32 (q, 12H), 6.87-7.96 (m, 162H).

SYNTHESIS EXAMPLE 2 Synthesis of Dendrimer 3

Dendrimer 3 in pale-yellow solid form was synthesized using 3.9 g (5.0mmol) of Compound C-7 and 0.54 g (1.0 mmol) of Compound C-9 in the samemanner as in the synthesis of Dendrimer 2. The structure of Dendrimer 3was identified using NMR spectroscopy. 1H-NMR (CDCl3, 400 MHz) δ (ppm);1.28 (t, 9H), 1.77 (s, 18H), 3.23 (q, 6H), 6.87-7.96 (m, 90H).

SYNTHESIS EXAMPLE 3 Synthesis of Dendrimer 4

A solution including 11.2 mL (32.0 g, 220 mmol) of brome and 80 mL ofCH₂Cl₂ was added to a solution including 16.7 g (100.0 mmol) ofcarbasole and 300 mL of CH₂Cl₂ at −30° C. for 30 minutes, and themixture was stirred at 0° C. for 5 hours. 200 mL of 10% NaHCO₃ aqueoussolution was added to the reaction mixture and the reaction mixture wassubjected to extraction twice with 300 mL of methylene chloride. Anorganic layer was dried, filtered, concentrated, and then separatedusing column chromatography to obtain 21.2 g of Compound C-9 in whitesolid form with a yield of 65%. The structure of Compound C-9 wasidentified using HR-MS. (calc.: 322.8945, found: 322.8945)

A mixture including 16.5 g (50.0 mmol) of Compound C-9, 44.0 g (200.0mmol) of 4-iodophenol, 0.48 g (0.05 mole %) of Cul, 0.66 g (0.05 mole %)of 18-C-6 (product name), and 400 mL of DMF was stirred at 130° C. for12 hours.

The reaction mixture was cooled to room temperature, 400 mL of methylenechloride was further added to the reaction mixture, and the reactionmixture was cleaned three times with 500 mL of water. An organic layerwas dried, filtered, concentrated, and then separated using columnchromatography to obtain 12.1 g of Compound C-10 in pale-yellow solidform with a yield of 58%. The structure of Compound C-10 was identifiedusing HR-MS. (calc.: 414.9270, found: 414.9270)

32.6 g of Compound C-12 in light-yellow solid form was synthesized witha yield of 78% using 20.9 g (100.0 mmol) of Compound C-11 and 33.7 g(100.0 mmol) of Compound C-2 in the same manner as in the synthesis ofCompound C-4. The structure of Compound C-12 was identified using HR-MS.(calc.: 418.2045, found: 418.2032)

13.5 g of Compound C-13 in light-yellow solid form was synthesized witha yield of 62% using 8.4 g (20.0 mmol) of Compound C-10 and 18.4 g (44.0mmol) of Compound C-12 in the same manner as in the synthesis ofCompound C-6. The structure of Compound C-13 was identified using HR-MS.(calc.: 1091.4774, found: 1091.4762)

80 mL of THF was added to a mixture including 10.9 g (10.0 mmol) ofCompound C-13, 770 mg (2.0 mmol) of pentaerythritol tetrabromide, and480 mg (20.0 mmol) of 95% NaH, and the mixture was stirred at roomtemperature for 1 hour and maintained at 50° C. for 6 hours. Thereaction mixture was cooled to room temperature, 30 mL of water wasfurther added to the reaction mixture, and the reaction mixture wassubjected to extraction twice with 100 mL of methylene chloride. Anorganic layer was dried, filtered, concentrated, separated using columnchromatography, and recrystallized to obtain 3.20 g of Dendrimer 4 inpale-yellow solid form with a yield of 46%. The structure of Dendrimer 4was identified using NMR spectroscopy. 1H-NMR (CDCl3, 400 MHz) δ (ppm);1.15 (t, 24H), 1.82 (s, 48H), 3.22 (q, 16H), 3.45 (s, 8H), 6.47-7.88 (m,152H).

SYNTHESIS EXAMPLE 4

Dendrimer 5 in pale-yellow solid form was synthesized with a yield of55% using 5.5 g (5.0 mmol) of Compound C-13 and 0.35 g (1.0 mmol) ofCompound C-14 in the same manner as in the synthesis of Dendrimer 4. Thestructure of Dendrimer 5 was identified using NMR spectroscopy. 1H-NMR(CDCl3, 400 MHz) δ (ppm); 1.18 (t, 18H), 1.82 (s, 3614), 3.33 (q, 12H),5.53 (s, 614), 6.87-7.96 (m, 117H).

EXAMPLE 1

To manufacture an anode, a Corning 15 Ω/cm² (1200 Å) ITO glass substratewas cut to a size of 50 mm×50 mm×0.7 mm and then sonicated in isopropylalcohol and pure water each for five minutes, and then cleaned byirradiation of ultraviolet (UV) rays for 30 minutes and exposure toozone. The resulting glass substrate was loaded into a vacuum depositiondevice.

A HIL was formed on the substrate by spin-coating a PEDOT/PSS aqueoussolution (produced by H.C.Starck) to a thickness of 40 nm. Then, a HTLwas formed on the HIL by spin-coating Dendrimer 2 to a thickness of 80nm. Then, a green fluorescent host (Alq3) and a green fluorescent dopant(C545T) were simultaneously deposited in a weight ratio of 98:2 on theHTL, to form an EML having a thickness of about 300 Å.

Then, Alq3 was deposited on the EML to form an ETL having a thickness ofabout 300 Å, and then LiF (which is halogenated alkali metal) wasdeposited on the ETL to form an EIL having a thickness of about 10 Å.Then, Al was vacuum-deposited on the EIL to a thickness of about 3000 Åto form a LiF/Al electrode (cathode), thereby completing the manufactureof an organic light-emitting device.

The organic light-emitting device had a driving voltage of 5.23 V at acurrent density of 50 mA/cm², a high luminance of 8,774 cd/m², colorcoordinates of (0.315, 0.682), and a luminescent efficiency of 17.11cd/A.

EXAMPLE 2

An organic light-emitting device was manufactured in the same manner asin Example 1, except that Dendrimer 3 was used instead of Dendrimer 2 toform the HTL.

The organic light-emitting device had a driving voltage of 5.67 V at acurrent density of 50 mA/cm², a high luminance of 8,445 cd/m², colorcoordinates of (0.310, 0.643), and a luminescent efficiency of 16.89cd/A.

EXAMPLE 3

An organic light-emitting device was manufactured in the same manner asin Example 1, except that Dendrimer 4 was used instead of Dendrimer 2 toform the HTL.

The organic light-emitting device had a driving voltage of 5.52 V at acurrent density of 50 mA/cm², a high luminance of 8,623 cd/m², colorcoordinates of (0.301, 0.665), and a luminescent efficiency of 17.24cd/A.

EXAMPLE 4

An organic light-emitting device was manufactured in the same manner asin Example 1, except that Dendrimer 5 was used instead of Dendrimer 2 toform the HTL.

The organic light-emitting device had a driving voltage of 5.24V at acurrent density of 50 mA/cm², a high luminance of 8,551 cd/m², colorcoordinates of (0.301, 0.663), and a luminescent efficiency of 17.10cd/A.

EXAMPLE 5

Dendrimer 2 and a green fluorescent dopant (C545T) were simultaneouslyspin-coated in a weight ratio of 98:2 on the HIL (PEDOT/PSS) instead ofthe HTL to form an EML having a thickness of 30 nm. Then, Alq3 wasdeposited on the EML to form an ETL having a thickness of about 300 Å,and then LiF (which is halogenated alkali metal) was deposited on theETL to form an EIL having a thickness of about 10 Å. Then, Al wasvacuum-deposited on the EIL to a thickness of about 3000 Å to form aLiF/Al electrode (cathode), thereby completing the manufacture of anorganic light-emitting device.

The organic light-emitting device had a driving voltage of 6.25 V at acurrent density of 50 mA/cm², a high luminance of 7,725 cd/m², colorcoordinates of (0.320, 0.643), and a luminescent efficiency of 15.45cd/A.

COMPARATIVE EXAMPLE 1

An organic light-emitting device was manufactured in the same manner asin Example 1, except that the HTL was not formed.

The organic light-emitting device had a driving voltage of 7.55 V at acurrent density of 50 mA/cm², a high luminance of 6,002 cd/m², colorcoordinates of (0.319, 0.652), and a luminescent efficiency of 12.0cd/A.

Characteristics such as color coordinates, luminance, and luminescentefficiency of the organic light-emitting devices are shown in Table 1below.

TABLE 1 Driving Current Voltage Density Luminance Efficiency Color HalfLife-span Dendrimer (V) (mA/cm²) (cd/m²) (cd/A) Coordinates (hr @ 100mA/cm²) Example 1 Dendrimer 2 5.23 50 8774 17.54 (0.315, 0.682) 470 hr(HTL) Example 2 Dendrimer 3 5.67 50 8445 16.89 (0.310, 0.643) 512 hr(HTL) Example 3 Dendrimer 4 5.52 50 8623 17.24 (0.301, 0.665) 528 hr(HTL) Example 4 Dendrimer 5 5.24 50 8551 17.10 (0.301, 0.663) 542 hr(HTL) Example 5 Dendrimer 2 6.25 50 7725 15.45 (0.320, 0.643) 310 hr(EML) Comparative — 7.55 50 6002 12.0 (0.319, 0.652) 231 hr Example 1

Driving voltages of the organic light-emitting devices manufacturedaccording to Examples 1 to 5 were lower than that of the organiclight-emitting device manufactured according to Comparative Example 1 bymore than 1 V, and the organic light-emitting devices manufacturedaccording to Examples 1 to 5 showed excellent I-V-L characteristics withhigh luminescent efficiency. In particular, life-spans of the organiclight-emitting devices manufactured according to Examples 1 to 4 weregreater than that of the organic light-emitting device manufacturedaccording to Comparative Example 1 by more than 100%. In addition, if adendrimer compound is used in an organic light-emitting device forforming an EML, the organic light-emitting device has low drivingvoltage and high emission efficiency, but life-span was not changed.

Since a dendrimer according to an embodiment has high electricalstability, excellent charge transporting capability, and high emissioncapability, it may be dissolved in an organic solvent to form a HIL or aHTL of an organic light-emitting device.

According to another embodiment, an organic light-emitting devicemanufactured using the dendrimer has high emission efficiency andexcellent luminance.

While the present embodiments have been particularly shown and describedwith reference to example embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present embodiments as defined by the following claims.

1. A dendrimer comprising a core unit, a bridge unit, and a dendronunit, wherein the core unit comprises a trivalent or tetravalentfunctional group selected from the group consisting of a substituted orunsubstituted C₁-C₅₀ aliphatic hydrocarbon, a substituted orunsubstituted C₅-C₅₀ aromatic hydrocarbon, and a substituted orunsubstituted C₃-C₅₀ hetero aromatic hydrocarbon, wherein the bridgeunit comprises a divalent or trivalent functional group selected fromthe group consisting of a substituted or unsubstituted C₅-C₅₀ aromatichydrocarbon and a substituted or unsubstituted C₃-C₅₀ hetero aromatichydrocarbon, and wherein the dendron unit comprises a monovalentfluorene-based functional group represented by Formula 1 below:

where Z is selected from the group consisting of a single bond,

Ar₁ and Ar₂ are each independently selected from the group consisting ofa single bond, a substituted or unsubstituted C₅-C₅₀ aryl group, and asubstituted or unsubstituted C₃-C₅₀ heteroaryl group, X₁ and X₂ are eachindependently selected from the group consisting of nitrogen (N), boron(B), and phosphorus (P), and X′ is selected from the group consisting ofoxygen (O), sulfur (S), SO₂, and CH₂, Y₁, Y₂, Y₃, Y₄, Y₅, and Y₆ areeach independently selected from the group consisting of a single bond,a substituted or unsubstituted C₁-C₅₀ alkylene group, a substituted orunsubstituted C₂-C₅₀ alkenylene group, a substituted or unsubstitutedC₂-C₅₀ alkynylene group, a substituted or unsubstituted C₃-C₅₀cycloalkylene group, a substituted or unsubstituted C₁-C₅₀ alkoxylenegroup, a substituted or unsubstituted C₅-C₅₀ arylene group, and asubstituted or unsubstituted C₃-C₅₀ heteroarylene group, R₁, R₂, R₃, R₄,and R₅ are each independently selected from the group consisting of ahydrogen atom, a deuterium, tritium, a halogen atom, a cyano group, anamino group, a nitro group, a hydroxyl group, a carboxyl group, asubstituted or unsubstituted C₁-C₅₀ alkyl group, a substituted orunsubstituted C₂-C₅₀ alkenyl group, a substituted or unsubstitutedC₂-C₅₀ alkynyl group, a substituted or unsubstituted C₃-C₅₀ cycloalkylgroup, a substituted or unsubstituted C₁-C₅₀ alkoxy group, a substitutedor unsubstituted C₅-C₅₀ aryl group, and a substituted or unsubstitutedC₃-C₅₀ heteroaryl group, and R′ and R″ are each independently selectedfrom the group consisting of a hydrogen atom, deuterium, tritium, ahalogen atom, a cyano group, an amino group, a nitro group, a hydroxylgroup, a carboxyl group, a substituted or unsubstituted C₁-C₅₀ alkylgroup, a substituted or unsubstituted C₅-C₅₀ aryl group, and asubstituted or unsubstituted C₃-C₅₀ heteroaryl group, wherein at leasttwo adjacent groups of R₁, R₂, R₃, R₄, R₅, and R″ are linked to form asaturated or unsaturated ring, and * is a binding site between oneselected from the group consisting of Ar₁, Z and a fluorene group andthe bridge unit.
 2. The dendrimer of claim 1, wherein Ar₁ and Ar₂ areeach independently selected from the group consisting of a single bond,a phenyl group, a halophenylene group, a cyanophenylene group, aphenoxyphenyl group, a C₁-C₁₅ alkyl phenyl group, a di(C₁-C₁₅ alkyl)phenyl group, a C₁-C₁₅ alkoxy phenyl group, a di(C₁-C₁₅ alkoxy) phenylgroup, a C₅-C₁₅ aryl phenyl group, a di(C₅-C₁₅ aryl) phenyl group, anaphthyl group, a halonaphthyl group, a cyanonaphthyl group, aphenoxynaphthyl group, a C₁-C₁₅ alkyl naphthyl group, a di(C₁-C₁₅ alkyl)naphthyl group, a C₁-C₁₅ alkoxy naphthyl group, a di(C₁-C₁₅ alkoxy)naphthyl group, a C₅-C₁₅ aryl naphthyl group, a di(C₅-C₁₅ aryl) naphthylgroup, an anthryl group, a haloanthryl group, a cyanoanthryl group, aphenoxyanthryl group, a C₁-C₁₅ alkyl anthryl group, a di(C₁-C₁₅ alkyl)anthryl group, a C₁-C₁₅ alkoxy anthryl group, a di(C₁-C₁₅ alkoxy)anthryl group, a C₅-C₁₅ aryl anthryl group, a di(C₅-C₁₅ aryl) anthrylgroup, a phenanthryl group, a halophenanthryl group, a cyanophenanthrylgroup, a phenoxyphenanthryl group, a C₁-C₁₅ alkyl phenanthryl group, adi(C₁-C₁₅ alkyl) phenanthryl group, a C₁-C₁₅ alkoxy phenanthryl group, adi(C₁-C₁₅ alkoxy) phenanthryl group, a C₅-C₁₅ aryl phenanthryl group, adi(C₅-C₁₅ aryl) phenanthryl group, a fluorenyl group, a halofluorenylgroup, a cyanofluorenyl group, a phenoxyfluorenyl group, a C₁-C₁₅ alkylfluorenyl group, a di(C₁-C₁₅ alkyl) fluorenyl group, a C₁-C₁₅ alkoxyfluorenyl group, a di(C₁-C₁₅ alkoxy) fluorenyl group, a C₅-C₁₅ arylfluorenyl group, a di(C₅-C₁₅ aryl) fluorenyl group, a pyridyl group, ahalopyridyl group, a cyanopyridyl group, a phenoxypyridyl group, aC₁-C₁₅ alkyl pyridyl group, a di(C₁-C₁₅ alkyl) pyridyl group, a C₁-C₁₅alkoxy pyridyl group, a di(C₁-C₁₅ alkoxy) pyridyl group, a C₅-C₁₅ arylpyridyl group, a di(C₅-C₁₅ aryl) pyridyl group, a pyrenyl group, ahalopyrenyl group, a cyanopyrenyl group, a phenoxypyrenyl group, aC₁-C₁₅ alkyl pyrenyl group, a di(C₁-C₁₅ alkyl) pyrenyl group, a C₁-C₁₅alkoxy pyrenyl group, a di(C₁-C₁₅ alkoxy) pyrenyl group, a C₅-C₁₅ arylpyrenyl group, a di(C₅-C₁₅ aryl) pyrenyl group, a phenanthrolinyl group,a halophenanthrolinyl group, a cyanophenanthrolinyl group, aphenoxyphenanthrolinyl group, a C₁-C₁₅ alkyl phenanthrolinyl group, adi(C₁-C₁₅ alkyl) phenanthrolinyl group, a C₁-C₁₅ alkoxy phenanthrolinylgroup, a di(C₁-C₁₅ alkoxy) phenanthrolinyl group, a C₅-C₁₅ arylphenanthrolinyl group, a di(C₅-C₁₅ aryl) phenanthrolinyl group, aquinolinyl group, a haloquinolinyl group, a cyanoquinolinyl group, aphenoxyquinolinyl group, a C₁-C₁₅ alkyl quinolinyl group, a di(C₁-C₁₅alkyl) quinolinyl group, a C₁-C₁₅ alkoxy quinolinyl group, a di(C₁-C₁₅alkoxy) quinolinyl group, a C₅-C₁₅ aryl quinolinyl group, a di(C₅-C₁₅aryl) quinolinyl group, a carbazolyl group, a halocarbazolyl group, acyanocarbazolyl group, a phenoxycarbazolyl group, a C₁-C₁₅ alkylcarbazolyl group, a di(C₁-C₁₅ alkyl) carbazolyl group, a C₁-C₁₅ alkoxycarbazolyl group, a di(C₁-C₁₅ alkoxy) carbazolyl group, a C₅-C₁₅ arylcarbazolyl group, and a di(C₅-C₁₅ aryl) carbazolyl group.
 3. Thedendrimer of claim 1, wherein Ar₁ and Ar₂ are each independentlyselected from the group consisting of a single bond, a phenyl group, ahalophenylene group, a cyanophenylene group, a biphenyl group, adimethylfluorenyl group, a carbazolyl group, and a diphenylcarbazolylgroup.
 4. The dendrimer of claim 1, wherein X₁ and X₂ are nitrogen (N).5. The dendrimer of claim 1, wherein Y₁, Y₂, Y₃, Y₄, Y₅, and Y₆ are eachindependently selected from the group consisting of a single bond, amethyl group, an ethyl group, a propyl group, an isobutyl group, asec-butyl group, a phenyl group, a methylphenyl group, an ethylphenylgroup, an o-, m- and p-fluorophenyl group, a dichlorophenyl group, acyanophenyl group, a dicyanophenyl group, a trifluoromethoxyphenylgroup, a biphenyl group, a halobiphenyl group, a cyanobiphenyl group, amethylbiphenyl group, an ethylbiphenyl group, a methoxybiphenyl group,and an ethoxybiphenyl group.
 6. The dendrimer of claim 1, wherein Y₁,Y₂, Y₃, Y₄, Y₅, and Y₆ are each independently selected from the groupconsisting of a single bond, a methyl group, an ethyl group, a propylgroup, an isobutyl group, a sec-butyl group, a phenyl group, and adiphenyl group.
 7. The dendrimer of claim 1, wherein R₁, R₂, R₃, R₄, R₅,R′, and R″ are each independently selected from the group consisting ofa hydrogen atom, deuterium, tritium, a halogen atom, a cyano group, anamino group, a methyl group, an ethyl group, a propyl group, an isobutylgroup, a sec-butyl group, a phenyl group, a methylphenyl group, anethylphenyl group, an o-, m- and p-fluorophenyl group, a dichlorophenylgroup, a cyanophenyl group, a dicyanophenyl group, atrifluoromethoxyphenyl group, a biphenyl group, a halobiphenyl group, acyanobiphenyl group, a methylbiphenyl group, an ethylbiphenyl group, amethoxybiphenyl group, and an ethoxybiphenyl group.
 8. The dendrimer ofclaim 1, wherein R₁, R₂, R₃, R₄, R₅, R′, and R″ are each independentlyselected from the group consisting of a hydrogen atom, deuterium,tritium, a halogen atom, a cyano group, an amino group, a methyl group,an ethyl group, a propyl group, an isobutyl group, a sec-butyl group, aphenyl group, and a biphenyl group.
 9. The dendrimer of claim 1, whereinthe fluorene-based functional group is selected from the groupconsisting of functional groups represented by Formulae 2 to 5 below:

where * is a binding site with the bridge unit.
 10. The dendrimer ofclaim 1, wherein the bridge unit comprises a functional group selectedfrom the group consisting of functional groups represented by Formulas 6to 9 below:

where ** is a binding site with an adjacent unit.
 11. The dendrimer ofclaim 1, wherein the core unit comprises a functional group selectedfrom the group consisting of functional groups represented by Formulas10 to 12 below:

where *** is a binding site with the bridge unit.
 12. The dendrimer ofclaim 1, wherein a number average molecular weight of the dendrimer isfrom about 1,000 to about 300,000.
 13. The dendrimer of claim 1, whereinthe dendrimer further comprises a surface unit that is selected from thegroup consisting of a substituted or unsubstituted C₅-C₅₀ aryl group anda substituted or unsubstituted C₃-C₅₀ heteroaryl group at the end of thedendron unit.
 14. The dendrimer of claim 1, wherein the dendrimer isselected from the group consisting of compounds represented by Dendrimer1 to 5 and has a number average molecular weight from about 1,000 toabout 30,000:


15. An organic light-emitting device comprising a pair of electrodes andan organic layer interposed between the electrodes, wherein the organiclayer comprises a dendrimer according to claim
 1. 16. An organiclight-emitting device comprising a pair of electrodes and an organiclayer interposed between the electrodes, wherein the organic layercomprises a dendrimer according to claim
 9. 17. An organiclight-emitting device comprising a pair of electrodes and an organiclayer interposed between the electrodes, wherein the organic layercomprises a dendrimer according to claim
 14. 18. The organiclight-emitting device of claim 15, wherein the organic layer comprisesat least one selected from the group consisting of an emission layer, ahole injection layer, and a hole transport layer.
 19. The organiclight-emitting device of claim 15, wherein the organic layer comprisesan emission layer.
 20. The organic light-emitting device of claim 15,wherein the dendrimer is used as a host of a green or red dopant.